trail - evidence pointing to a possible solution; the police are following a promising lead; the trail led straight to the perpetrator track, lead evidence, grounds - your basis for belief or disbelief; knowledge on which to base belief; the evidence that smoking causes lung cancer is very compelling
The process by which the oceanic crust is pulled under the continental crust is called subduction and the zone at which this occurs at the plate boundaries is called the subduction zone. At the subduction zone where the oceanic crust sinks beneath the continental crust a deep oceanic trench or valley is created.
When an oceanic plate collides with a continental plate the crust forming the oceanic plate gets bent and pulled under the continental crust. This is because the rocks that form the oceanic crust are denser and thinner than the rocks that form the continental crust.